Non-volatile memory devices, such as NAND flash memory devices, may use read voltage thresholds to distinguish between discrete stored data values. However, stored read voltage levels may drift over time, due to charge leakage, due to read disturb and/or program disturb effects, or the like.
Adjustments to read voltage thresholds may be made to account for changes in stored read voltage levels, to prevent or correct errors. Certain encodings for data, especially data stored in storage cells that store many bits of data, have multiple bit transition points from 1 to 0 or from 0 to 1 for each page stored by the storage cells. Multiple bit transitions can make it difficult to quickly and efficiently determine an adjustment for a read voltage threshold, since it may not be readily apparent over which read voltage threshold the stored voltage level has crossed.